Re: [PATCH v2 1/3] perf report: Change sort order by a specified event in group

[Jin, Yao]

On 12/11/2019 7:38 PM, Jiri Olsa wrote:
> On Wed, Dec 11, 2019 at 03:30:34PM +0800, Jin Yao wrote:
>
> SNIP
>
> > +
> > +static int __hpp__group_sort_idx(struct hist_entry *a, struct hist_entry *b,
> > +				 hpp_field_fn get_field, int idx)
> > +{
> > +	struct evsel *evsel = hists_to_evsel(a->hists);
> > +	u64 *fields_a, *fields_b;
> > +	int cmp, nr_members, ret, i;
> > +
> > +	cmp = field_cmp(get_field(a), get_field(b));
> > +	if (!perf_evsel__is_group_event(evsel))
> > +		return cmp;
> > +
> > +	nr_members = evsel->core.nr_members;
> > +	ret = pair_fields_alloc(a, b, get_field, nr_members,
> > +			      &fields_a, &fields_b);
> > +	if (ret) {
> > +		ret = cmp;
> > +		goto out;
> > +	}
> > +
> > +	for (i = 1; i < nr_members; i++) {
> > +		if (i == idx) {
> > +			ret = field_cmp(fields_a[i], fields_b[i]);
> > +			if (ret)
> > +				goto out;
> > +		}
> > +	}
> > +
> > +	if (cmp) {
> > +		ret = cmp;
> > +		goto out;
> > +	}
> > +
> > +	for (i = 1; i < nr_members; i++) {
> > +		if (i != idx) {
> > +			ret = field_cmp(fields_a[i], fields_b[i]);
> > +			if (ret)
> > +				goto out;
> > +		}
>
> hi,
> I'm missing why we compare the fields for 2nd time in here
>
> thanks,
> jirka

Hi,

I think we may continue comparing the remaining of fields if the index 
field is equal. :)

Thanks
Jin Yao